Strong abdominal muscles play an important role in many health aspects, including also back pain, which is frequently caused by an imbalance between the strength of the back and abdominal muscles, up to supporting the correct position of internal organs.
Exercises for strengthening of the abdominal muscles range from sit-ups and crunches, which require almost no exercising device, up to use of devices—exercise devices, which exercise abdominal muscles in a seated or in a supine position.
These exercise devices for strengthening of the abdominal muscles apply the exercise principle of sit-ups and crunches, while providing a possibility of creating a load during the exercise.
Such devices are disclosed e.g. in U.S. Pat. No. 5,419,750; US 2003/0060347 A1; U.S. Pat. No. 7,481,752 B2 and U.S. Pat. No. 7,172,541 B2.
Document U.S. Pat. No. 5,419,750 discloses a device for exercising of mainly the abdominal part of the body, and strengthening of the abdominal muscles, where a repeated sit-up movement is performed against the power of a hydraulic piston. The device comprises a frame with a central longitudinal part provided with legs at its ends, and a bench for the user is placed on this central part, substantially horizontally, actually with a slight declination. The declination of the bench causes the head of the user to be lower than his lower body part when lying on the bench. An extension member is attached perpendicularly to the central longitudinal part, on which an arm is pivotally connected. One end of the arm is bent over the bench and the other end is mounted to the hydraulic piston. Supports for the exerciser's legs are attached to the legs of the frame. The exerciser, when exercising on this device, is seated at the center of the bench near the perpendicular extension member, puts his legs under the leg supports and the end of the arm bent over the bench is held at his chest. The exerciser then performs sit-up exercise against the power of the hydraulic piston mounted at the other end of the pivotally connected arm.
Document US 2003/0060347 A1 discloses a device for strengthening of the abdominal muscles, which comprises a base frame composed of two, for the purpose of length adjustment, opposing moving frames. A footplate for a user's legs is mounted on the second frame of the base frame, and a seat for the user and a pivoted back support are mounted on the first frame of the base frame. The back support has a lower part mounted on a supporting frame, which is pivoted to the first base frame and an upper part of the back support is pivoted to a lower part of the back support. Two handlebars extend from the frame of the upper back support at the upper side, which the user holds by his hands. Between the supporting frame of the back support and the first part of the base frame a damping device in the form of a hydraulic or pneumatic cylinder is provided. The user, when exercising on this device, is seated on the seat, puts his legs against the footplate, leans his back against the back support and holds the handlebars at the upper part of the back support. With this device, the user performs a sit-up exercise, while the damping device in one instance creates resistance against muscle strength, thus strengthening the abdominal muscles, and further dampens the speed of the movement of the back support, whereby no sudden pressure is developed on the neck of the user and therefore this device is safe for use.
Document U.S. Pat. No. 7,481,752 B2 discloses a device for strengthening of abdominal muscles, which is composed of a frame on which the user is seated, the frame has a support arm tilted backward from vertical, with the lower lumbar region of the user against a seat member. The upper part of the seat member assembly is pivotally attached to the frame. The upper part of the seat assembly has a pair of handles and a pad designed to lay against the upper back of the user. The seat back assembly moves with the upper back of the user, and the hands of the user assist in maintaining the upper seat back member against the upper back, while the user moves from a tilted back position to a crunch position, and simulating a traditional sit-up movement. A hydraulic or pneumatic member is attached between the upper part of the seat back assembly and the base of the device, which creates a resistance force when the upper back rest assembly moves with the movement of the user. The hydraulic or pneumatic member is placed so as to provide the smallest resistance force at the beginning of the exercise, i.e. when the torso is lifted, and to increase the resistance force while the torso is moved to an upright position, when the body force needed to overcome the weight of the torso decreases.
Document U.S. Pat. No. 7,172,541 B2 discloses an abdominal exercise machine, having a floor supported bench and a mast pivotally connected to an end of the bench. A pair of double acting hydraulic cylinders are pivotally connected between the end of the bench and the mast. A footrest assembly is connected to the mast. A recumbent exerciser exercises abdominal muscles by pushing and pulling the mast against the resistance of the hydraulic cylinders.
Sit-up exercises with anchored feet besides exercising the abdominal muscles also exercises the hip flexors. This exercise increases pressure on the lumbar region. A sit-up exercise with feet freely put on the ground does not allow the use of external resistance, which is necessary for stimulation of muscle fibers while increasing the strength of abdominal muscles. Crunches exercise abdominal muscles isolatedly, but not in the whole range of motion. The mentioned exercises show these disadvantages also when performed on exercise devices, which are basically developed according to movements performed during sit-up exercises and crunches.
The mentioned disadvantages are eliminated by an exercise device for strengthening of the abdominal muscles disclosed in US 2007/0149371 A1 of the same applicant, which comprises a frame to which a press arm is connected rotatively in a vertical plane. To the press arm a resistance mechanism is connected, preferably a hydraulic cylinder, which exerts resistance force only in a direction against downward movement of the press arm. Free end of the arm can move in a range of motion from a user's waist area to the user's ankles. This device strengthens abdominal muscles isolatedly, while the user is standing. However, no undesired stress on the spine occurs, i.e. the press arm is not loaded when it is lifted (upward movement) and thus no extra stress is applied to the spine as it is e.g. when lifting a weight. However, a disadvantage of this device is that a user exercising on the device lacks the feeling of exercising of the abdominal muscles, as occurs with sit-up exercises and crunches. The user thus perceives exercising on this device as insufficient, or without an effect. This device also, as the user is standing, employs weight of the torso to overcome the resistance force, which decreases the effect of the exercise when exercising on this device.
An object of the invention is to provide a device for strengthening of the abdominal muscles, which applies the principle of sit-up exercises and crunches when exercising the abdominal muscles, wherein exercising on such a device does not have the disadvantages of the traditional sit-up exercises and crunches, performed either without or with use of the exercising device, and performed either without or with an additional resistance force.
It is also an object of the invention to provide a device, which removes a pressure developed on the lumbar region when bending the torso during exercising of the abdominal muscles.
An object of the invention is also a device for strengthening of abdominal muscles, which substantively eliminates disadvantages of devices known from prior art.
Another object of the invention is effective use of an isokinetic resistance mechanism in a device for strengthening of abdominal muscles.